This bug was reported to Keith a few days ago, and he could not fix it, so flicked it off to someone else. The bug works on PC and Mac when you change the start channel to the #universe:chan or >item:chan and you then click to sequencer tab, but ONLY when the whole house window is open.
It's an old bug as it happened to me late last year too, while changing a few items from channel number starts to #universe:chan amd >item:chan setups, b ut I never worked out the actual cause until about 2 weeks ago while away sequencing